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# *HELP* AS Maths Edexcel Trigonometry watch

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1. Alright so I have this question and I’m completely stuck on it. I can’t seem to get my value of x to be = to what it wants in question part a. I used angles in a triangle to figure out the other angle which is 45 I then used sine rule and solved algebraically but it’s not working for me.

All help and solutions appreciated!

The diagram shows triangle ABC with AC=8x-3, BC=4x-1, angle ABC=120 degrees and angle ACB=15 degrees.

(a) Show that the exact value of x is 9+√6/20 (7 marks)
(b) Find the area of triangle ABC giving your answer to 2 decimal places
(3 marks)
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2. Can you post a diagram and I'll help you.
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4. (Original post by fabalas)
Use the sine rule:

Sin 120/(8x - 3) = sin 45/(4x - 1)

You should know exact values for sin 120 and sin 45.
5. (Original post by fabalas)
Alright so I have this question and I’m completely stuck on it. I can’t seem to get my value of x to be = to what it wants in question part a. I used angles in a triangle to figure out the other angle which is 45 I then used sine rule and solved algebraically but it’s not working for me.

All help and solutions appreciated!

The diagram shows triangle ABC with AC=8x-3, BC=4x-1, angle ABC=120 degrees and angle ACB=15 degrees.

(a) Show that the exact value of x is 9+√6/20 (7 marks)
(b) Find the area of triangle ABC giving your answer to 2 decimal places
(3 marks)
Did you get the equation to be

{2/sqrt(3)}(8x-3) = {sqrt(2)}(4x-1) ?

Solving this equation gives you the required value of x.
6. a) Sine rule. I'll work in terms of sin for you:

4x-1 / sin45 = 8x-3 / sin 120
--> 4x sin120 - sin120 = 8x sin45 - 3sin45
--> 4x sin120 - 8x sin45 = sin120 - 3sin45
--> x[4sin120 - 8sin45] = sin120 -3sin45

--> x = sin120 - 3sin45 / (4sin120-8sin45) = 9 + root 6 / 20, QED.

I want you to complete the steps I missed purposefully.
7. Thank you so much! That’s helped a lot!
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8. where is this question from?
(Original post by fabalas)
Alright so I have this question and I’m completely stuck on it. I can’t seem to get my value of x to be = to what it wants in question part a. I used angles in a triangle to figure out the other angle which is 45 I then used sine rule and solved algebraically but it’s not working for me.

All help and solutions appreciated!

The diagram shows triangle ABC with AC=8x-3, BC=4x-1, angle ABC=120 degrees and angle ACB=15 degrees.

(a) Show that the exact value of x is 9+√6/20 (7 marks)
(b) Find the area of triangle ABC giving your answer to 2 decimal places
(3 marks)
9. (Original post by Revisionwithmae)
where is this question from?
It’s from the edexcel trig milestone, I had the question in the milestone test and had to complete improvements on it.
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